Add a recursion depth limit, similar to if_gif.c; also, when computing the route for the GRE tunnel, verify that it does not point back to ourselves.
Add a recursion depth limit, similar to if_gif.c; also, when
computing the route for the GRE tunnel, verify that it does not point
back to ourselves.

orumin/openbsd-efivars,orumin/openbsd-efivars,orumin/openbsd-efivars,orumin/openbsd-efivars